update maven site plugin
diff --git a/pom.xml b/pom.xml
index cd5ef6a..3d109bd 100644
--- a/pom.xml
+++ b/pom.xml
@@ -68,8 +68,7 @@
     <mavenVersion>3.0</mavenVersion>
     <checkstyleVersion>8.29</checkstyleVersion>
     <doxiaVersion>1.4</doxiaVersion>
-    <sitePluginVersion>3.7.1</sitePluginVersion>
-    <project.build.outputTimestamp>2020-02-08T08:24:16Z</project.build.outputTimestamp>
+    <sitePluginVersion>3.9.0</sitePluginVersion>    <project.build.outputTimestamp>2020-02-08T08:24:16Z</project.build.outputTimestamp>
   </properties>
 
   <contributors>